Keyed collet



July 28, 1959 V J, ANN 2,896,956

KEYED COLLET Filed Dec. 13, 1957 ,41. B52 TA u. A/v/v,

United States Patet This invention relates generally to devices for holding tools such as milling cutters, carbide bun-s, abrasive wheels, etc. More particularly, the invention has reference to a collet equipped with a key means adapted to engage the collet-supported tool, to prevent the tool from dropping out of the collet.

Considerable difiiculty is experienced, in the perform- 7 ance of operations involving tools of the character generally described above, in respect to preventing the tool from dropping accidentally out of a collet. This difliculty is experienced mainly with tools having straight shanks, such as the ordinary milling cutter, whether of the single or double type. Obviously, not only is the performance of the work operations slowed considerably by reason of this occurrence, but also, damage to the work or to the tool can result, and other undesirable results can occur, as well.

'The main object of the present invention is to eliminate the difficulties noted above, and tothis end, the invention, summarized briefly, comprises a col-let which in general has the exteriorand internal configuration of an ordinary collet. In accordance with the invention, a novelly shaped key is insertable in any of a plurality of angularly spaced, radial slots of the collet, said key engaging not only in the selected slot, but also, in a groove provided in the tool that is to be held, said groove being in registration with the slot for engagement of the key with both the tool and the collet. The particular form of the key, slot, and groove are such as to produce a coactive relationship among the several components, that insures against accidental dropping of the tool out of the collet, while still not interfering with the ordinary tightening and loosening action of the collet upon the tool, or the performance of the usual work operations.

Other objects will appear from the following description, the claims appended thereto, and from the annexed drawing, in which like reference characters designate like parts throughout the several views, and wherein:

Figure l is a front elevational view of a collet according to the present invention;

Figure 2 is a side elevational view thereof;

Figure 3 is a transverse sectional view on line 33 of Figure 2;

Figure 4 is a longitudinal sectional view substantially on line 4-4 of Figure l, a supported tool being illustrated partly in elevation and partly in longitudinal section, the adjacent, collet-holding component of the machine being illustrated fragmentarily and in dotted lines;

Figure 5 is a transverse section on line 55 of Figure 4; and

Figure 6 is a perspective view of the key per se.

Referring to the drawing in detail, designated generally at 10 is a machine which might be any of various types, it being mainly important for the purpose of the present invention that the machine be of the type holding a collet 12 in the manner shown in Figure 4. The machine might be a lathe, a milling machine, or other related apparatus, as will be readily understood.

In any event, the collet includes a body 14 comparatively short in length in relation to its maximum diameter, said body from its inner or rear end, shown as the left hand end in Figure 4, being progressively increased in diameter as at 16, to a location between the midlength point and the forward or outer end of the collet. At this location, the collet body begins to taper toward the forward end thereof as at 18. In other words, the body is progressively increased in diameter from its opposite ends to a location intermediate its ends, said location being nearer to one than to the other end of the collet.

The opposite end surfaces 20, 22 of the collet are cut off squarely, being disposed wholly in planes perpendicular to the axis of the collet.

Designated at 24 are longitudinally extending, narrow, deep radial slots of the collet. These slots, as shown in Figure 4, are extended the full length of the collet, and at opposite ends of each slot there are formed shoulders 25 extending parallel to the longitudinal center line or axis of the collet, in closely spaced relation to the axial bore 27 of the collet.

Intermediate the shoulders 25, each slot 24 has communication with a passage 26, of substantial length, said passage communicating between the slot and the bore 27. Passage 26 is of a width the same as that of the slot, as will be obvious from Figure 5 as well as from Figure 3.

Insertable in any of the slots 24 is a key 28, shown per se in Figure 6. In length, the key is coextensive with the slot 24 as clearly seen from Figure 4. Further, the key has sloped top edge surfaces 28a, 28b, which are flush with the surfaces 16, 18 when the key is inserted in the slot. Still further, the key has a depending projection 30, extending downwardly from a projection 31.

It will be seen that the key has its projection 31 terminating short of opposite ends of the key, so that beyond opposite ends of the projection 31, there are surfaces 31a, 31b, which are in a common plane and which bear against the shoulders 25. Thus, the projection 31 is coextensive in length with the passage 26, so as to fit snugly into said passage as seen in Figure 4. The projection 30 has one end registered with one end of projection 31, the other end of the projection 30 terminating short of the corresponding other end of the projection 31. The projection 30, therefore, will project radially, inwardly within bore 27, in the inserted position of the key.

The projection 30 will extend into a longitudinal groove 32 formed in the shank 34 of a rotary tool such as a milling cutter, etc., said tool having a head 36. The illustrated tool is merely one example of a tool with which the invention can be used. There of course are many others, and it is not desired that the invention be limited to use with any particular tool.

In any event, it will be noted that the collet also has a longitudinal, radially disposed slot 38, which extends fully into communication with bore 27. This is the only slot into which the key may not be inserted. This slot is for the purpose of permitting contraction of the collet to the tool, after the tool has been inserted and the key 'interengaged with the tool shank and with the collet.

It will be observed that in use, with the key removed, the tool shank is inserted into the bore 27. Then, with groove 32 in registration with a selected slot 24 (it makes no difference which slot 24 is used), the key 28 is inserted, so that it necessarily becomes disposed as in Figure 4, with its projection engaged in the groove 32, and its shoulders 31a, 31b bearing against shoulders 25 of the slot 24.

In this way, when the collet is contracted to the work, the tool shank will be held against accidentally dropping out of the collet bore 27, and, since the collet itself will be radially contracted, the contraction of the collet to the tool shank tends to shift key'28 in a direction circumferentially of the bullet, enough to laterally 'offset the 'key in respect to the groove 32, 50 as to securely, frictionally,

bind the key within the groove and within the associated slot '24. Such ofls'etting of'the keyis so minute as to .not be visible to'the naked eye, "but nevertheless exists to an extent suflicient to securely bind thekeyin'place.

The 'key of course is loosened sufiiciently to' be removed, responsive .to intentional loosening of the 'coll et in respect to the tool shank, so that the hey 'carr' 'be removed'to permit removal of 'the'to'ol shank.

It may also be noted that at each end of the collet an unbroken annular (portion extending about bore 27,

unbroken, that is, except for-the slot 38. By reason of this arrangement, .there is provided at each end of the tcolletbodya ring portion which,-in.effect, constitutes a split clamping ring contractible into gripping engagement with the tool shank.

It is believed apparent that-the inventionis not necessarily confinedtothe specific use oruses thereof described above, since it may be'utilized for any purpose to which it 'maybesuited. Nor is'the invention to be necessarily limited to the specific construction illustrated and described, since such construction is only intended to be illustrative of-the principles, it .being considered that .the invention 'comprehends any minor 'changein construction that may beperrnittedwithin thescope of the appended claims.

What is claimed is:

A collet for engaging a'toolshank having a longitudinal groove, comprising: ascollet body adapted to be grippedby "a .collet holder and formed with ;a side surface and body, 'the shoulders '25 at said end extend as n'ngs'about '41 r with end surfaces, said body having an axial bore opening 'upon both --end surfaces for *receivingsaid shank, said body having a plurality of'identical, longitudinally extending, narrow, deep, radial slots opening at their ends upon the respective end surfaces and opening over their full lengths upon said side surface, the slots at their ends extending, in the sense of a direction radially of the lgody, from said side surface toa'aj location spaced radially outwardly from said bore, whereby to define shoulders at opposite ends of each slot, the "slots extending the full radial distancefromathetside sur-faceltotsaidrbore throughout the ,p0rtions of wthe lengths of the slots. disposed between the "shoulders; anda key '-selectively"insertable in any one of the slots .aud extending-:theifull length of the body with its ends flush with said end surfaces, said key having an outer longitudinal edge flush with the side surface to hold the key against displacement in a direction radially outwardly .of the body when thecollet is gripp'ed insaidholder, thekey havinga'projectionpn its inner longitudinal 'edge extending radially inwardlyof'th'e here to 'eng'agein saidl'grooveofthe shank,'thekey having at its opposite ends angular surfaces complenlientary"to said shoulders and engaging the same to 'hold the key againstdisplacement both longitudinally of the'bo'dyzand rupted solely by the last-named slot, over the full "'ci'rtcmnference of "the body at the ends thereof;

Re'ferences"Cited in the. file of this patent UNITED STATES PATENTS 1,230,561 'Chige :'Iun'e 19, I917 1",7 153097 Redinger ..:May 28, 1929 15839569 Lovejoy itan-5,1932 2;465;'4 3-3' =Doni'ger 'Mar. 29,194? 

